Myths And Facts About Strengthening Your Immune System

In an effort not to get sick, many people seek out ways to strengthen their immunity. Since researchers don’t fully understand the immune system, many “immune-boosting” tactics have little to no scientific backing. They’re myths, not facts.

To enhance your immune system, you’ll have to debunk the myths and learn the facts. Learn the truth–and fiction–about immune-boosting diets. See whether a fever helps or harms your body’s immunity, and understand what role sleep plays. You can help improve your health by reading these immune system myths and facts.

MYTH: Exercise Worsens The Immune System

Some health websites assert that exercise weakens the immune system, but science says the opposite. A 2018 study concluded that working out lowers your risk of viral and bacterial infections, according to Frontiers in Immunology. Moderate exercise makes your body stronger overall.

A man wipes away sweat after exercising on a fitness trail.
BSIP/Universal Images Group via Getty Images
BSIP/Universal Images Group via Getty Images

However, you don’t want to over-exercise. According to a study in the Exercise Immunology Review, over-exerting yourself lowers the immune system. “Exercise helps boost the immune system, but we have to be careful not to overexercise because it can weaken your immune system,” says medical director Elizabeth Bradley.

FACT: A Healthy Diet Can Help Keep You Well

Research suggests that the immune system needs a certain amount of vitamins to fight illnesses. During a 2018 study in Frontiers of Immunology, participants who were nutrient-deficient were more susceptible to disease. When they got sick, these participants suffered more and longer, the study says.

Cucumber, parsley, tomatoes, and lettuce are washed in water.

Immune-boosting minerals include: vitamin A, iron, zinc, B vitamins, copper, vitamin C, vitamin D, and essential amino acids. You can receive these nutrients through a healthy, varied diet. But beware that some vitamins can increase your likelihood of disease, according to Advanced Pharmaceutical Bulletin.

MYTH: Antibacterial Foods Prevent Illness

Foods that are advertised as “antibacterials,” “superfoods,” or “immune-boosting” claim to strengthen the immune system. But that is not true, says professor of immunology Charles Bangham. Since the immune system includes several organs and bodily systems, it’ll take more than a good diet to keep it strong.

A woman eats avocado toast with greens on top.
Brendon Thorne/Getty Images for Virgin Mobile
Brendon Thorne/Getty Images for Virgin Mobile

The same applies to supplements claim to “stimulate” the immunity. A hyperactive immune system can create disease symptoms, after all. “If a supplement stimulated the innate immune response, it would leave you with a constant feeling of being unwell,” Dr. Bangham explains.

MYTH: Daily Vitamins Help Your Immune System

Although many people take vitamins to boost their immune system, it could make things worse. According to the Journal of Leukocyte Biology, taking vitamins daily for a long time can make the immune system “forget.” The body gets used to being handed nutrients, so it stops naturally producing enough to handle an infection.

A pill organizer contains vitamins and medication for each day of the week.
Jeffrey Greenberg/Education Images/Universal Images Group via Getty Images
Jeffrey Greenberg/Education Images/Universal Images Group via Getty Images

Also, there is no solid evidence that one supplement will improve your immunity, says Harvard Health Publishing. Unless you’re deficient in a certain nutrient, you probably don’t need vitamins. You already get enough minerals from food.

FACT: Lack Of Sleep Can Make You Sick

People who struggle to sleep will also struggle to fight off disease. After reviewing over 120 studies, researchers concluded that sleep schedules are “strong regulators of immunological processes.” In short, a regular sleep schedule will keep your immune system strong.

A woman struggles to sleep in bed.

According to the National Sleep Foundation, sleep produces and releases cytokines, a protein that attacks inflammation caused by infection. If you get fewer than seven hours of sleep, your body may not be able to guard against disease. For the sake of your immune system, try to get enough sleep.

MYTH: The Flu Vaccine Makes You Sick

It’s a myth that flu vaccines weaken your immune system. The Centers for Disease Control (CDC) tests the flu vaccine every year, and recently, it has lowered rates of illness by 40% to 60%. It even prevents hospitalization from pneumonia by up to 70%.

A woman vaccinates an older man against influenza.
Marcelo Hernandez/Getty Images
Marcelo Hernandez/Getty Images

Vaccines introduce a small version of the virus into your body, and the immune system learns how to defeat it. As a result, the body can fight off viruses later. The American Academy of Pediatricians says that the vaccine works best in healthy adults, but it also helps children above six months old.

FACT: The Immune System Extends Throughout The Body

The immune system isn’t one organ. According to Live Science, immunity involves the lymphatic system, which includes the spleen, bone marrow, thymus, and lymph nodes. Certain blood cells and bacteria in the body also contribute to the immune system. It’s one of the most complex systems in the body.

An artistic illustration shows a person raising a hand against bacteria.
Carmen McKnight/Pinterest
Carmen McKnight/Pinterest

Dr. Erika Schwartz adds that gut bacteria can also aid the immune system. That’s why eating certain foods can weaken the body against certain diseases. To keep your immune system healthy, you’ll have to take care of your entire body.

FACT: Dirt Is Good

A recent hygiene hypothesis argues having kids play in dirt strengthens their immune system. And most health professionals agree. “We are getting far too sterile,” says microbiologist Kiran Krishnan. “Most of our immune system is comprised of tissue that requires activation by the microbes we’re exposed to.”

A child plays in dirt with a toy truck.

The immune system needs to encounter bacteria if it wants to learn how to fight them. In this sense, it isn’t dirt that helps kids’ immune systems, but the microbes in a natural environment. The takeaway? Don’t be too clean.

MYTH: Fevers Make You More Prone To Illness

Although some people believe that fevers weaken the immune system, this is a myth. In 2011, a study in the Journal of Leukocyte Biology concluded that a higher body temperature strengthens immune cells. Heat triggers Nuclear Factor kappa B (NF-κB), a signaling pathway that activities immune cells.

A man gets his temperature checked with a thermometer in his ear.

This is why colds and flus don’t often appear in summer, explains researcher Mike White. His 2018 animal study in PNAS noticed that animals became less sick in hotter temperatures. In this sense, fevers truly “burn off” illness.

FACT: As We Age, Our Immune System Weakens

Older adults are more vulnerable to viruses and bacteria. According to The Journal of Clinical Investigation, immune cells decrease as people age, although the amount varies per person. Bolstering your immune system can delay this decline.

A senior citizen clutches a walking cane.

“Your age is the primary determinant of what’s going to happen to your immune system,” says biomedical research professor Philippa Marrack. Even so, older immune systems are more experienced in fighting illnesses that you’ve had before, Marrack adds. So there are some advantages to an aged immunity.

MYTH: If Your Immune System Is Active, You’re Healthy

When your immune system is active, that doesn’t necessarily mean you’re healthy. A hyperactive immune system can react to ordinary substances, making you allergic to something you could previously handle, explains the University of Rochester Medical Center.

An artistic depiction shows immune cells.

Over time, the immune system can also stop working. Robert Shmerling, a medical editor of Rheumatoid Arthritis, says that immunity malfunctions during long bouts of rheumatoid arthritis. Scientists still aren’t sure why this happens, but they know that hyperactive immune systems exist in chronic conditions such as diabetes and lupus.

MYTH: Too Many Vaccines Weaken Immunity

Some people believe that having too many vaccines at once can hurt the immune system, but this isn’t true. According to the World Health Organization, there is no scientific evidence that piling on vaccines causes harm. Often, children are prescribed several shots to become immunized as early as possible.

A researcher works on the development of a vaccine.
DOUGLAS MAGNO/AFP via Getty Images
DOUGLAS MAGNO/AFP via Getty Images

The CDC lists several advantages to having simultaneous vaccinations. One is that children get protection quickly. Another is that it prevents trauma for children. And it’s safe to vaccinate simultaneously, so why not?

FACT: Stress Makes You Vulnerable

Some people get sick as soon as they get busy. That isn’t in their head; stress can weaken the immune system. Clinical immunologist Leonard Calabrese explains that stress lowers the number of lymphocytes, white blood cells that help fight off infection. Research in the journal Psychological Bulletin backed this up.

A man presses his hand against his temples.

However, occasional stress can boost your immunity. According to an animal study in Psychoneuroendocrinology, stress releases immune cells and trains your body for infections. Chronic stress harms your immune system, but occasional stress helps it.

MYTH: Antibiotics Support The Immune System

Since it’s medicine, antibiotics help the immune system, right? Wrong. In 2018, scientists from Case Western Reserve University noted that antibiotics kill “good” bacteria. Normally, these bacteria would support immune cell growth and combat inflammation. But antibiotics destroy them.

A person holds antibiotics next to a glass of water.
Rafael Henrique/SOPA Images/LightRocket via Getty Images
Rafael Henrique/SOPA Images/LightRocket via Getty Images

That said, antibiotics are usually introduced when the body can’t fight the illness alone, says immunologist and allergist Kathleen Dass. If you’re prescribed an antibiotic, there’s likely a good reason for it. You can take probiotics with the medication if you want to re-introduce good bacteria.

MYTH: A Weak Immune System Creates Seasonal Allergies

Allergies don’t result from a weak immune system. If anything, they stem from the body reacting too strongly to allergens. According to John Hopkins Medicine, when the body contacts something it’s allergic to, it releases antibodies to attack the allergen. The result is a runny nose, itchy eyes, and cough.

A woman blows her nose behind a large plant.

Of course, there are different causes of allergies. Some are the immune system’s hyper-responsiveness to certain substances, such as dust and pollen. Another cause is sensitization, when a substance hits the body for so long that it creates inflammation.

Fact: Salt Can Harm The Immune System

In March 2020, German researchers discovered that eating too much salt can have sickly consequences. During the study, participants who ate over one teaspoon of salt per day had a high risk of infections, diseases, and other health complications. Most of their salt came from packaged or processed foods.

A person pours salt from a shaker.
Karl-Josef Hildenbrand/picture alliance via Getty Images
Karl-Josef Hildenbrand/picture alliance via Getty Images

When you over-consume salt, the immune systems struggle to fight off illness, says the journal Science Translational Medicine. Christian Kurts, one of the researchers, says that the dangerous amount equals two meals of a burger and fries.

MYTH: The Body Builds Natural Immunity Without Vaccines

Some people avoid vaccines, believing that their immune systems will develop naturally. Technically, this can be true, but the risks outweigh the benefits. “If you don’t take vaccines, you will build immunity but only by getting sick—and in certain cases, potentially gravely ill,” Dr. Arielle Levitan, the co-founder of Vous Vitamin.

Immune cells attack cancer cells in this artistic depiction.

By contracting diseases to build immunity, you risk a one in 500 chance of death, says Public Health. With a vaccine, you have a one in a million chance of dying, according to the World Health Organization. In short, you’re far better off with a vaccine.

FACT: Weight Impacts The Immune System

Scientists say that being overweight or obese can devastate the immune system. In 2010, Australian researchers discovered that losing weight reduced the symptoms of type 2 diabetes. According to them, excess fat triggers pro-inflammatory immune cells that could damage the body.

A man steps on a scale.
Joan Slaking/Education Images/Universal Images Group via Getty Images
Joan Slaking/Education Images/Universal Images Group via Getty Images

These findings pose some concerns for researchers since the rate of obesity is rapidly increasing. “The situation has reached crisis point, and people must be made aware that excess fat will affect their immune systems and therefore their survival,” says researcher Katherine Samaras.

MYTH: Skip “Dehydrating” Coffee When You’re Sick

Since hydration helps people fight off illness, some people avoid consuming “dehydrating” drinks–such as coffee–while sick. But coffee can help your body stay healthy. A study in the Journal of Psychopharmacology found that coffee reduces the grogginess from a cold.

A breakfast tray features coffee, a sandwich, and the newspaper on an iPad.
Getty Images
Getty Images

Since coffee has high antioxidants, a cup or two can encourage the immune system, says registered dietitian Ashley Reaver. The downside? Caffeinated coffee can keep you awake when you should be sleeping, Reaver says. Drink “dehydrating” beverages in moderation, and you’ll be fine.

MYTH: Everyone Is Born With The Same Immune System

Although it seems like everyone has the same immunity, that’s not true. In 2015, a study in Cell found that immune systems develop throughout peoples’ lives. During the study, participants responded differently to a flu shot based on their environmental factors and genetics.

A young woman lies sick in bed.

According to a 2016 study in Nature Immunology, peoples’ immune systems change as they live with other people. Our immunity constantly adjusts to our environment. Plus, people with auto-immune disorders struggle to fight off disease more than others.